The present invention pertains to the field of playback of streaming media such as audio and audio-visual works which are retrieved from sources having non-deterministic delays such as, for example, a server such as a file server or a streaming media server, broadcasting data via the Internet. In particular, the present invention pertains to method and apparatus for providing playback of an audio or audio-visual work received from sources having non-deterministic delays. In further particular, the present invention pertains to method and apparatus for providing continuous playback of streaming media from sources having non-deterministic delays such as, for example, a server such as a file server or a streaming media server, broadcasting data via the Internet, an Intranet, or the like.
Many digitally encoded audio and audio-visual works are stored as data on servers such as file servers or streaming media servers that are accessible via the Internet for users to download. FIG. 1 shows, in schematic form, how such audio or audio-visual works are distributed over the Internet. As shown in FIG. 1, media broadcast server 2000 accesses data representing the audio or audio-visual work from storage medium 2100 and broadcasts the data to multiple recipients 23001 to 2300n across non-deterministic delay network 2200. In this system there are two main sources of random delay: (a) delay due to the broadcast server""s accessing storage medium 2100 and (b) delay due to the congestion, interference, and other delay mechanisms within network 2200.
One well known technique for providing playback of the audio or audio-visual work is referred to as batch playback. Batch playback entails downloading an entire work and initiating playback after the entire work has been received. Another well known technique for providing playback of the audio or audio-visual work is referred to as xe2x80x9cstreaming.xe2x80x9d Streaming entails downloading data which represents the audio or audio-visual work and initiating playback before the entire work has been received.
There are several disadvantages inherent in both of these techniques. A prime disadvantage of batch playback is that the viewer/listener must wait for the entire work to be downloaded before any portion of the work may be played. This can be tedious since the viewer/listener may wait a long time for the transmission to occur, only to discover that the work is of little or no interest soon after playback is initiated. The streaming technique alleviates this disadvantage of batch playback by initiating playback before the entire work has been received. However, a disadvantage of streaming is that playback is often interrupted when the flow of data is interrupted due to network traffic, congestion, transmission errors, and the like. These interruptions are tedious and annoying since they occur randomly and have a random duration. In addition, intermittent interruptions often cause the context of the playback stream to be lost as a user waits for playback to be resumed when new data is received.
As one can readily appreciate from the above, a need exists in the art for a method and apparatus for providing substantially continuous playback of streaming media such as audio and audio-visual works received from sources having non-deterministic delays such as a server, for example, a file server or a streaming media server, broadcasting data via the Internet.
Embodiments of the present invention advantageously satisfy the above-identified need in the art and provide method and apparatus for providing substantially continuous playback of streaming media such as audio and audio-visual works received from sources having non-deterministic delays such as a server, for example, a file server or a streaming media server, broadcasting data via the Internet.
One embodiment of the present invention is an apparatus for preparing streaming media such as an audio or audio-visual work for playback which comprises: (a) a buffer which stores data corresponding to the streaming media; (b) a buffer monitor which determines an amount of data stored in the buffer; (c) a rate determiner, in response to output from the buffer monitor, that determines a playback rate; and (d) a time-scale modification system, responsive to the playback rate, that time-scale modifies at least a portion of the data in the buffer. In further embodiments, a playback system plays back the time-scale modified data as a portion of the streaming media.